I made some custom modifications to a plugin. When we get a notice that there is an official upgrade for this plugin in WP, a dev needs to manually do the upgrade because the changed files have to be integrated with the new version.
We don't want a staff member to accidentally click the upgrade button on this plugin while going through a series of upgrades.
However, we still want to see the upgrade notification, so that a dev can schedule the update. So increasing the version number in the header to some really high value is not a solution, because it blocks that visibility.
How can I block WP from being able to upgrade and the plugin still be valid?